The therapeutic effect of L-5-hydroxytryptophan (L-5HTP) in combination with a decarboxylase inhibitor, carbidopa, is being evaluated in diseases associated with myoclonic muscle movements and related neurological disorders. Modification of this therapeutic regimen such as the use of chlorimipramine and the use of benserazide in place of carbidopa are also being evaluated. In addition to routine blood tests and urinanalysis, the metabolism of L-5HTP in these patients is being measured in the urine, blood and central nervous system. The effect of L-5HTP and carbidopa on endocrine function is also being measured. Investigations of the mechanisms of action of L-5HTP and carbidopa in relieving myoclonus are being studied in animal models. The possible role of serotoninergic neutrons in the production of this neurological symptom and the metabolic changes involved will be investigated. BIBLIOGRAPHIC REFERENCES: Van Woert, M.D., Rosenbaum, D., Howieson, J. and Bowers, M.B. Jr. Long-term therapy of myoclonus and other neurological disorders with L-5-hydroxytryptophan and carbidopa. New Eng. J. Med. 296, 70-74, 1977. Van Woert, M.H., Yip, L.C. and Balis, M.E. Purine phosphoribosyltransferase in Gilles de la Tourette syndrome. New Eng. J. Med. 296, 210-212, 1977.